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Old 11th June 2018, 10:23 AM   #11
victordascalescu54 is offline victordascalescu54  Romania
diyAudio Member
 
Join Date: Jan 2018
Location: Bucharest, Romania, EU
Now I stared up with my restoration.
First stepp was measuring resistors (all of them) Pulling out the tubes I asume i can check all of them without unsoldering. The result was not verry promising as many of them were out of 10% tolerance.
The worst were:
R2=166k(220k)
R3=115k(100k)
R5=30,7(33)
R7=380k(680k)
R8=378k(680k)
R9=14k(68k) can be a mesuring fault, I have to unslder
R10=41k(33k)
R11=18k(47k) can be a mesuring fault, I have to unslder
R15=123k(100k)
R19=206k(470k)
R25=452k(470k)
R25=121k(100k)
R27=52k(47k)
R30=815k(680k)
R36=56k(47k)
R38=12k(10k)
All cheramic capacitors I asume are all right
The electrolotics I have allready changed all with modern one as well as the C47 and C53 with MKp.
As I intend to use an external MPX decoder from Fisher(MPX 100) I did not care about the internal decoder compoments.
Your opinion shall be usefull to me. Shall I change all resistors or else?
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Old 13th June 2018, 07:21 AM   #12
victordascalescu54 is offline victordascalescu54  Romania
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Join Date: Jan 2018
Location: Bucharest, Romania, EU
I had remake the calculations, Lawrence was right, large part of resistors revial better tolerances than 10%. Nevertheless R9 was too low and athers where too high especialy R3, R10, R26, R27, R30, R36 R38, Which I suppose are out of range. I shal start slowly, slowly to unsolder and change them with Kiwame as they are carbon type and claim to be noninductive. I can use also AB as I have a lott but I am afraid not to be so stabile.
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Old 14th June 2018, 06:11 AM   #13
ej25awd is offline ej25awd  Canada
formally hitachi_nut
 
Join Date: Jan 2007
Location: BC
Before you start removing parts and upgrading them to supposed better ones, do you have an FM stereo generator that you can use to align this tuner?

Some of the parts of this tuner have been selected for specific characteristic not just the capacitors. Replacing them with a part that has a different temperature coefficient for example will result in undesirable drift, etc.
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Old 14th June 2018, 06:45 AM   #14
victordascalescu54 is offline victordascalescu54  Romania
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Join Date: Jan 2018
Location: Bucharest, Romania, EU
Quote:
Originally Posted by ej25awd View Post
Before you start removing parts and upgrading them to supposed better ones, do you have an FM stereo generator that you can use to align this tuner?

Some of the parts of this tuner have been selected for specific characteristic not just the capacitors. Replacing them with a part that has a different temperature coefficient for example will result in undesirable drift, etc.
Unfortunately I don't have the gear to realign. But some resistors values are far out of the specs. Nevertheless, the tuner works but I am especting much better sound as I have heard one sonding excelent. This one sonds dull, lack of dinamics and space.
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Old 14th June 2018, 08:53 AM   #15
ej25awd is offline ej25awd  Canada
formally hitachi_nut
 
Join Date: Jan 2007
Location: BC
Alignment will yield better sound than replacing parts on a misaligned tuner.
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Old 17th June 2018, 04:19 PM   #16
victordascalescu54 is offline victordascalescu54  Romania
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Join Date: Jan 2018
Location: Bucharest, Romania, EU
Quote:
Originally Posted by ej25awd View Post
Alignment will yield better sound than replacing parts on a misaligned tuner.
I know, but how can I make the difrence ? How can I see/hear the tuner is missaligned ?
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Old 19th June 2018, 07:12 AM   #17
ej25awd is offline ej25awd  Canada
formally hitachi_nut
 
Join Date: Jan 2007
Location: BC
You said it yourself "This one sonds dull, lack of dinamics and space."

Replacing all the resistors is not going to fix all of these.

Yours have a dull sound which might be due to excessive high frequency roll off. The only way to figure this out is to measure the tuner's frequency response and this requires an FM generator, audio generator and a meter, all these should be of better accuracy and linearity than the tuner. Once you have the frequency response data, you can figure out where the highs are being rolled off. Blanket parts replacement which is what you are planning will introduce new sets of problems. Fix a problem one at a time and avoid adding more problem.

Lack of dynamics might be due to the unit sounding thin and missing the low end. Majority of FM tuners have excessive low frequency phase shift and roll off. Some have "flat" frequency response from 50Hz-15kHz but exhibit poor frequency and phase response below 50Hz. Most stations in my area have audio content down to 30Hz with a few all the way down to 20Hz.

Lack of space, you mean separation? This problem can be addressed with alignment and at times modification. Some tuners have compromised design that severely affect stereo separation. Old muliplex decoder designs found in most tube designs requires the use of SCA filters. These SCA filters have a nasty effect of significantly reducing stereo separation from 1kHz to 15kHz. The SCA filter cut off is too close to the upper limit of the multiplex/composite signal of 53kHz. It is just impossible to have a notch at the SCA sub-carrier of 67kHz and achieve a flat frequency and group delay response from 20Hz-53kHz.

A mis-aligned tuner can exhibit different symptoms. It can be the center tuning meter not in sync with the signal strength meter, the dial indicator being off by a significant amount across the dial, harsh grainy sound, collapsed stereo imaging, noisy, poor sensitivity, etc.

FM tuners are far more complex than amplifiers. If you don't possess the skills and equipment, it is better to leave this to someone who does.
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Old 19th June 2018, 07:37 AM   #18
victordascalescu54 is offline victordascalescu54  Romania
diyAudio Member
 
Join Date: Jan 2018
Location: Bucharest, Romania, EU
Quote:
Originally Posted by ej25awd View Post
You said it yourself "This one sonds dull, lack of dinamics and space."

Replacing all the resistors is not going to fix all of these.

Yours have a dull sound which might be due to excessive high frequency roll off. The only way to figure this out is to measure the tuner's frequency response and this requires an FM generator, audio generator and a meter, all these should be of better accuracy and linearity than the tuner. Once you have the frequency response data, you can figure out where the highs are being rolled off. Blanket parts replacement which is what you are planning will introduce new sets of problems. Fix a problem one at a time and avoid adding more problem.

Lack of dynamics might be due to the unit sounding thin and missing the low end. Majority of FM tuners have excessive low frequency phase shift and roll off. Some have "flat" frequency response from 50Hz-15kHz but exhibit poor frequency and phase response below 50Hz. Most stations in my area have audio content down to 30Hz with a few all the way down to 20Hz.

Lack of space, you mean separation? This problem can be addressed with alignment and at times modification. Some tuners have compromised design that severely affect stereo separation. Old muliplex decoder designs found in most tube designs requires the use of SCA filters. These SCA filters have a nasty effect of significantly reducing stereo separation from 1kHz to 15kHz. The SCA filter cut off is too close to the upper limit of the multiplex/composite signal of 53kHz. It is just impossible to have a notch at the SCA sub-carrier of 67kHz and achieve a flat frequency and group delay response from 20Hz-53kHz.

A mis-aligned tuner can exhibit different symptoms. It can be the center tuning meter not in sync with the signal strength meter, the dial indicator being off by a significant amount across the dial, harsh grainy sound, collapsed stereo imaging, noisy, poor sensitivity, etc.

FM tuners are far more complex than amplifiers. If you don't possess the skills and equipment, it is better to leave this to someone who does.
Thank you, every thing is clear now but unfortunately there is noboady left in my country to have the gear and to know how. Nevertheless I shall not give up searching for.
During that time, I started cheking the tubes as I have a nice micro Tracer and the result was:
V1(ecc88) verry good, both sections more tha 100%
V2(ecc85) one section 60% and the ather 50%
V3(ecf80) accetable both sections but pentode was 70%
V4(ef80) 60%
V5(ecf80) accetable both sections but pentode was 70%
V6(em84) ok
V7(ez80)80% both diodes
As the stereo decoder was not a big thing I was listening first in mono from the cathode folower out and then using the external Fisher MPX 100 using a direct conection from the tuner mpx out prior to C51...this one was better than the germanium decoder but still kack of "life"
Shall I replace the tubes first?
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